Abstract
Phytase (myo-inositol-hexakisphosphate phosphohydrolase, (EC 3.1.3.8) has been purified from a novel isolated Bacillus cereus EME 48, from environmental samples based on their ability. The enzymes were purified and characterized, using a three-step purification procedure with 12.3-fold. The optimum pH for phytase activity was in the range of 4.0 to 5.0 and the optimum temperature was 40 to 60 degrees C for 10 min. The metal ions MgCl2, CoC(l)2, NiCl2 and KCl2 did not show any inhibitory effect on the phytase activity of Bacillus cereus EME 48. Strongly inhibited by FeCl2, Na Florida, EDTA, DTT, AlCl2 and ZnCl2, but significantly stimulated by MgCl2, BaCl2 ,MnCl2 and CuCl2. The enzymes were active in the pH range of 5.0 to 6.5 with pH optima at 5.5. The enzyme from Bacillus cereus EME 48 retained about 80% activity up to 75 degrees C. It was highly specific to sodium phytate as the substrate. Km for phytate was estimated to be 0.23 mmol and especially for penta- and tri-phosphate esters of myo-inositol. Due to their relatively high specific activity, substrate specificity, good pH profile and thermostability, the enzymes could be interesting candidate for agricultural and feed application.